Download Organ systems of the worm HW 11/25

What Are the Seven Organ Systems of the Earthworm
by Rob Hainer, Demand Media
Earthworms need damp soil to keep their skin moist. Earthworms are simple creatures that pack a powerful
environmental punch. They live in moist soil, digging tunnels that aerate the soil for plants and processing
vegetation through their digestive systems to turn it into nutrients for the plant roots. Earthworms do all this
with basic organ systems.
Respiratory System
Earthworms don't have lungs like mammals do. Instead, they breathe by diffusing air directly through their
skin. Oxygen passes in while carbon dioxide passes out. Their skin must stay moist for the gas diffusion to
work properly, which is why they stick to damp soil and don't usually venture out into the hot sunshine.
Circulatory System
An earthworm has a closed circulatory system that uses vessels to send blood through its body. There are
five aortic arches throughout his body that serve as pumps. The dorsal vessels take blood from the back of
his body to the front, and the ventral vessels take blood the other direction, from front to back. Smaller
capillaries (small veins) help the blood absorb nutrients and oxygen or carbon dioxide and carry them to the
proper areas of his body.
Muscular System
For such a small creature, an earthworm has a powerful muscular system. Long muscles that run along his
length help trigger a wave of movement from smaller muscles that circle the body in segments. The circular
muscles squeeze inward while stretching out to the sides, going in waves down the earthworm's body. This
pushes his body forward.
Digestive System
Digestion takes place in nearly a straight line down the earthworm's body. When he ingests food, he
swallows it until it passes through the gizzard, which uses tiny stones to grind up the food and pass it onto
the intestines. In the intestines, the beneficial pieces are absorbed and the waste passed to the excretory
system.
Excretory System
Part of an earthworm's excretory system is directly connected to his digestive system, as the
intestines pass waste through the anus and out of the worm. This poop is called castings, and it
serves as a type of plant fertilizer. However, some of the waste is picked up by excretory cells and
carried outward to the skin. This waste is secreted through the skin as mucus that helps keep the
worm's skin moist.
Nervous System
Earthworms have nerve clusters that are connected to a nerve cord that run down the worm's
length. The nerves transmit electrical signals from the nerve cord to various other systems, such as
telling the muscles to contract or the gizzard to start grinding food.
Reproductive System
An earthworms needs to mate with another worm to produce eggs, but they don't have to look for a
specific gender. Most earthworms are hermaphrodites, which means they carry both male and
female reproductive organs. To mate, the earthworms basically exchange sperm. Then, each
earthworm lays eggs fertilized by the other's sperm.
External Anatomy (Use your dissection Terms page)
2. The top (side we see) of the earthworm is the ___________________ side. This is the darker side of the
worm.
3. The bottom (belly) of the earthworm is the _____________ side. This is the lighter side of the worm.
4. The __________________ part of the earthworm is the head region.
5. The _________________ part of the earthworm is the tail region. There is an anus at the tail region.
6. If you were discussing the top half (mid-way to the top) of the worm you would be talking about the
________________ part of the worm.
7. If you were discussing the bottom half (mid-way to the end) of the worm you would be talking about the
________________ part of the worm.
Invertebrate
Vertebrate
About
Animals without a backbone
Animals with an internal skeleton made of
bone are called vertebrates.
Kingdom
Animalia
Animalia
Physical
Multicellular; no back bone; no cell walls;
Characteristics reproduce sexually; heterotrophic.
Multi-cellular, Well-developed internal
skeleton(backbone); highly developed brain;
have advanced nervous system; reproduce
sexually; heterotrophic.
Examples
Parrots, Humans, snakes etc
Insects, flatworms etc.
Classification 30 different major groups
Classified into five major groups: fish,
amphibians, reptiles, birds, and mammals.
Size
Small and slow moving.
Big in size.
Species
98% of animal species are invertebrates.
2% of the animal species are vertebrates.
Number of
species
2 million
57,739
Classify each creature with either a V for Vertebrate, or an I for Invertebrate.
1. Monkey ______
6. Chicken ______
2. Clam ______
7. Goldfish _______
3. Grasshopper ______
8. Ant _______
4. Rattlesnake ______
9. Starfish _______
5. Crocodile ______
10. Dolphin _______
External Anatomy (Use your dissection Terms page)
2. The top (side we see) of the earthworm is the ___________________ side. This is the darker side of the
worm.
3. The bottom (belly) of the earthworm is the _____________ side. This is the lighter side of the worm.
4. The __________________ part of the earthworm is the head region.
5. The _________________ part of the earthworm is the tail region. There is an anus at the tail region.
6. If you were discussing the top half (mid-way to the top) of the worm you would be talking about the
________________ part of the worm.
7. If you were discussing the bottom half (mid-way to the end) of the worm you would be talking about the
________________ part of the worm.
Lunbricus Questions:
1.
The earth worm is a ___________________________________ meaning it has no
backbone.
2.
What type of cells does a worm have? Eukaryotic or Prokaryotic
3.
All animals need oxygen. Since earthworms don’t have lungs, how do they get their
oxygen?
4.
What is the main food source for worms?
5.
Put the worm parts in order that food travels from beginning to end. (esophagus,
gizzard, mouth, anus, pharynx, crop, intestine)
6.
How do worms move?
7.
Earthworms are sensitive to what three things?
8.
Do earthworms have eyes? Explain.
9.
Earthworms reproduce _________________________________________ which means they
require ______________________________________________________________________.
10.
Earthworms are hermaphroditic which means each worm has two sex organs,
____________________ and _______________________.